The present invention is directed to an apparatus for preventing contamination of a bicycle control cable and, more specifically, to a protective cap and cover system for preventing deterioration of the cable as a result of the penetration of foreign matter.
Bicycle front and rear brakes and derailleurs are operated by control cables connected to shift lever units or brake levers located on the handle bars. Control cables are constructed of an inner cable that is slidingly disposed within an outer casing. The inner cable is made by twisting several steel wires together. The outer casing is ordinarily constructed of a synthetic resin cable liner, a band steel strip that is spirally wound around the cable liner, and a synthetic resin jacket that is used to cover the outer circumference of the band steel strip. The outer casing usually terminates at a position midway between the shifting lever unit or brake lever and the rear or front derailleur, thus leaving the inner cable exposed.
The inner cable is exposed for the following reasons. A gap typically is formed between the outer circumferential surface of the inner cable and the inner circumferential surface of the cable liner to allow the inner cable to slide more easily. In the case of longer cables, however, the friction force increases between the inner cable and cable liner, imposing a burden on the operation of the shift lever unit or the brake lever. The outer casing is therefore removed at a certain point to prevent such excessive friction.
However, foreign objects, such as mud, dust, etc., penetrate from the exposed end of the cable into the gap, thus increasing the slide resistance between the inner cable and cable liner. As a result, the brakes or shift mechanism, etc., becomes more difficult to operate. Furthermore, foreign objects such as clay and sand in mud act as grinding materials, causing the cable liner and inner cable to wear more quickly. Contamination of the gap between the inner cable and the outer casing thus should be avoided wherever possible.
The applicant has already proposed protective end caps for outer cables in Japanese Laid-Open Patent Application 63-173512. Such caps are attached to outer casings in order to prevent the penetration of foreign objects inside the cable. However, the use of many such caps on a single control cable increases the resistance in operating the inner cable. Furthermore, because the cable is exposed, the cable can deteriorate from moisture and other contaminants.